The modern automotive internal combustion engine has been recognized as a principal contributor to atmospheric pollution. Devices of various sorts have been developed to control release of crankcase emissions and remove harmful products from the exhaust gases. However, it has long been recognized that if the engines could be made to operate so that substantially complete combustion of the engine fuel occurred under all operating conditions, not only would the amount of objectionable pollutants be substantially reduced, the power output of the engine and fuel economy would be increased.
In order to achieve maximum power output or the best fuel economy from an internal combustion engine, the proper fuel/air ratio, by weight, must be maintained. A carburetor will provide an engine with the proper fuel/air ratio during a portion of the operating range, but not during all driving modes, and only for a given air density. If the fuel/air ratio is permitted to become too rich or too lean, the power output of the engine is considerably reduced. Also, the ignition timing will either be too fast or too slow and the spark plug heat range will be affected. To maintain a balance of these conditions, and secure maximum power output at a given density, the correct fuel/air ratio must be maintained.
Efforts to calibrate carburetors lean enough to meet the required levels of hydrocarbons, carbon monoxide, and nitrogen oxide have not been entirely satisfactory, since as the mixture ratio is made leaner, the cylinder-to-cylinder mixture distribution becomes increasingly sensitive. This may result in an excessively lean condition in some of the cylinders, causing misfiring and raw fuel to pass through the engine, increasing the HC level and reducing engine efficiency, power, and fuel economy.
Substantially improved results have been obtained with the valves and air supply systems of the aforementioned MacGuire U.S. Pat. Nos. 3,693,650, 3,799,132, and 4,024,846 which supply air pulsations to the engine manifold of an internal combustion engine over substantially the entire speed range of the engine for improved engine response and acceleration. Such valves and sustems provide automatic adjustment to various throttle settings and rates of acceleration or deceleration, which in the past have commonly resulted in a temporary improper fuel/air mixture, and prevent the emission of excessive pollutants to the atmosphere, particularly carbon monoxide and hydrocarbon vapors.
When properly adjusted, the valves can be made to resonate over the full operating range of the engine, that is, during idle as well as during cruising and acceleration and deceleration. As the valves resonate, air pulsations are created causing turbulence in the air flow passing through the valves and into the carburetor where pressure waves are set up in the lower part of the carburetor and manifold. These pressure valves assist in breaking up the fuel into smaller, more uniform particle sizes in addition to maintaining a more constant air/fuel mixture over the full operating range, for improved combustion, efficiency, fuel economy, and lower exhaust emissions.